597 lines
17 KiB
C
597 lines
17 KiB
C
/*
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** $Id: llex.c $
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** Lexical Analyzer
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** See Copyright Notice in lua.h
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*/
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#define llex_c
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#define LUA_CORE
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#include "lprefix.h"
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#include <locale.h>
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#include <string.h>
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#include "lua.h"
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#include "lctype.h"
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#include "ldebug.h"
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#include "ldo.h"
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#include "lgc.h"
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#include "llex.h"
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#include "lobject.h"
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#include "lparser.h"
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#include "lstate.h"
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#include "lstring.h"
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#include "ltable.h"
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#include "lzio.h"
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// 获取下一个字符
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#define next(ls) (ls->current = zgetc(ls->z))
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// 当前字符是新行吗？
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#define currIsNewline(ls) (ls->current == '\n' || ls->current == '\r')
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/* ORDER RESERVED */
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static const char *const luaX_tokens [] = {
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"and", "break", "do", "else", "elseif",
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"end", "false", "for", "function", "goto", "if",
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"in", "local", "nil", "not", "or", "repeat",
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"return", "then", "true", "until", "while",
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"//", "..", "...", "==", ">=", "<=", "~=",
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"<<", ">>", "::", "<eof>",
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"<number>", "<integer>", "<name>", "<string>"
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};
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// 把当前字符保存到缓冲区，并且读取下一个字符
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#define save_and_next(ls) (save(ls, ls->current), next(ls))
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// 报错
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static l_noret lexerror (LexState *ls, const char *msg, int token);
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// 把当前字符保存到缓冲区
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// 如果超出缓冲区大小，则更新缓冲区大小
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static void save (LexState *ls, int c) {
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Mbuffer *b = ls->buff;
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if (luaZ_bufflen(b) + 1 > luaZ_sizebuffer(b)) {
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size_t newsize;
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if (luaZ_sizebuffer(b) >= MAX_SIZE/2)
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lexerror(ls, "lexical element too long", 0);
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newsize = luaZ_sizebuffer(b) * 2;
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// 这里会重新申请内存
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luaZ_resizebuffer(ls->L, b, newsize);
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}
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b->buffer[luaZ_bufflen(b)++] = cast_char(c);
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}
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void luaX_init (lua_State *L) {
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int i;
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// 创建一个新的字符串
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TString *e = luaS_newliteral(L, LUA_ENV); /* create env name */
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luaC_fix(L, obj2gco(e)); /* never collect this name */
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for (i=0; i<NUM_RESERVED; i++) {
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// 创建保留字字符串
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TString *ts = luaS_new(L, luaX_tokens[i]);
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// 永远不要回收保留字字符串
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luaC_fix(L, obj2gco(ts)); /* reserved words are never collected */
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// 字符串对应的符号码，ts->extra+255== RESERVED
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ts->extra = cast_byte(i+1); /* reserved word */
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}
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}
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const char *luaX_token2str (LexState *ls, int token) {
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if (token < FIRST_RESERVED) { /* single-byte symbols? */
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if (lisprint(token))
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return luaO_pushfstring(ls->L, "'%c'", token);
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else /* control character */
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return luaO_pushfstring(ls->L, "'<\\%d>'", token);
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}
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else {
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const char *s = luaX_tokens[token - FIRST_RESERVED];
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if (token < TK_EOS) /* fixed format (symbols and reserved words)? */
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return luaO_pushfstring(ls->L, "'%s'", s);
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else /* names, strings, and numerals */
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return s;
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}
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}
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static const char *txtToken (LexState *ls, int token) {
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switch (token) {
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case TK_NAME: case TK_STRING:
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case TK_FLT: case TK_INT:
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save(ls, '\0');
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return luaO_pushfstring(ls->L, "'%s'", luaZ_buffer(ls->buff));
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default:
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return luaX_token2str(ls, token);
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}
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}
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static l_noret lexerror (LexState *ls, const char *msg, int token) {
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msg = luaG_addinfo(ls->L, msg, ls->source, ls->linenumber);
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if (token)
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luaO_pushfstring(ls->L, "%s near %s", msg, txtToken(ls, token));
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luaD_throw(ls->L, LUA_ERRSYNTAX);
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}
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l_noret luaX_syntaxerror (LexState *ls, const char *msg) {
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lexerror(ls, msg, ls->t.token);
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}
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/*
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** Creates a new string and anchors it in scanner's table so that it
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** will not be collected until the end of the compilation; by that time
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** it should be anchored somewhere. It also internalizes long strings,
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** ensuring there is only one copy of each unique string. The table
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** here is used as a set: the string enters as the key, while its value
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** is irrelevant. We use the string itself as the value only because it
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** is a TValue readily available. Later, the code generation can change
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** this value.
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*/
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TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
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lua_State *L = ls->L;
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TString *ts = luaS_newlstr(L, str, l); /* create new string */
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const TValue *o = luaH_getstr(ls->h, ts);
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if (!ttisnil(o)) /* string already present? */
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ts = keystrval(nodefromval(o)); /* get saved copy */
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else { /* not in use yet */
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TValue *stv = s2v(L->top.p++); /* reserve stack space for string */
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setsvalue(L, stv, ts); /* temporarily anchor the string */
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luaH_finishset(L, ls->h, stv, o, stv); /* t[string] = string */
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/* table is not a metatable, so it does not need to invalidate cache */
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luaC_checkGC(L);
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L->top.p--; /* remove string from stack */
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}
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return ts;
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}
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/*
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** increment line number and skips newline sequence (any of
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** \n, \r, \n\r, or \r\n)
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*/
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static void inclinenumber (LexState *ls) {
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int old = ls->current;
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lua_assert(currIsNewline(ls));
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next(ls); /* skip '\n' or '\r' */
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if (currIsNewline(ls) && ls->current != old)
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next(ls); /* skip '\n\r' or '\r\n' */
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if (++ls->linenumber >= MAX_INT)
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lexerror(ls, "chunk has too many lines", 0);
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}
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void luaX_setinput (lua_State *L, LexState *ls, ZIO *z, TString *source,
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int firstchar) {
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ls->t.token = 0;
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ls->L = L;
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ls->current = firstchar;
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ls->lookahead.token = TK_EOS; /* no look-ahead token */
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ls->z = z;
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ls->fs = NULL;
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ls->linenumber = 1;
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ls->lastline = 1;
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ls->source = source;
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ls->envn = luaS_newliteral(L, LUA_ENV); /* get env name */
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luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER); /* initialize buffer */
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}
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/*
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** =======================================================
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** LEXICAL ANALYZER
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** =======================================================
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*/
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static int check_next1 (LexState *ls, int c) {
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if (ls->current == c) {
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next(ls);
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return 1;
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}
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else return 0;
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}
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/*
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** Check whether current char is in set 'set' (with two chars) and
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** saves it
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*/
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static int check_next2 (LexState *ls, const char *set) {
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lua_assert(set[2] == '\0');
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if (ls->current == set[0] || ls->current == set[1]) {
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save_and_next(ls);
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return 1;
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}
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else return 0;
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}
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/* LUA_NUMBER */
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/*
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** This function is quite liberal in what it accepts, as 'luaO_str2num'
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** will reject ill-formed numerals. Roughly, it accepts the following
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** pattern:
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**
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** %d(%x|%.|([Ee][+-]?))* | 0[Xx](%x|%.|([Pp][+-]?))*
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**
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** The only tricky part is to accept [+-] only after a valid exponent
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** mark, to avoid reading '3-4' or '0xe+1' as a single number.
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**
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** The caller might have already read an initial dot.
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*/
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static int read_numeral (LexState *ls, SemInfo *seminfo) {
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TValue obj;
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const char *expo = "Ee";
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int first = ls->current;
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lua_assert(lisdigit(ls->current));
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save_and_next(ls);
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if (first == '0' && check_next2(ls, "xX")) /* hexadecimal? */
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expo = "Pp";
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for (;;) {
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if (check_next2(ls, expo)) /* exponent mark? */
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check_next2(ls, "-+"); /* optional exponent sign */
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else if (lisxdigit(ls->current) || ls->current == '.') /* '%x|%.' */
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save_and_next(ls);
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else break;
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}
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if (lislalpha(ls->current)) /* is numeral touching a letter? */
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save_and_next(ls); /* force an error */
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save(ls, '\0');
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if (luaO_str2num(luaZ_buffer(ls->buff), &obj) == 0) /* format error? */
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lexerror(ls, "malformed number", TK_FLT);
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if (ttisinteger(&obj)) {
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seminfo->i = ivalue(&obj);
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return TK_INT;
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}
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else {
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lua_assert(ttisfloat(&obj));
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seminfo->r = fltvalue(&obj);
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return TK_FLT;
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}
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}
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/*
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** read a sequence '[=*[' or ']=*]', leaving the last bracket. If
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** sequence is well formed, return its number of '='s + 2; otherwise,
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** return 1 if it is a single bracket (no '='s and no 2nd bracket);
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** otherwise (an unfinished '[==...') return 0.
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*/
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static size_t skip_sep (LexState *ls) {
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size_t count = 0;
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int s = ls->current;
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lua_assert(s == '[' || s == ']');
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save_and_next(ls);
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while (ls->current == '=') {
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save_and_next(ls);
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count++;
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}
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return (ls->current == s) ? count + 2
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: (count == 0) ? 1
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: 0;
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}
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static void read_long_string (LexState *ls, SemInfo *seminfo, size_t sep) {
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int line = ls->linenumber; /* initial line (for error message) */
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save_and_next(ls); /* skip 2nd '[' */
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if (currIsNewline(ls)) /* string starts with a newline? */
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inclinenumber(ls); /* skip it */
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for (;;) {
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switch (ls->current) {
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case EOZ: { /* error */
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const char *what = (seminfo ? "string" : "comment");
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const char *msg = luaO_pushfstring(ls->L,
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"unfinished long %s (starting at line %d)", what, line);
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lexerror(ls, msg, TK_EOS);
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break; /* to avoid warnings */
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}
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case ']': {
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if (skip_sep(ls) == sep) {
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save_and_next(ls); /* skip 2nd ']' */
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goto endloop;
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}
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break;
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}
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case '\n': case '\r': {
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save(ls, '\n');
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inclinenumber(ls);
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if (!seminfo) luaZ_resetbuffer(ls->buff); /* avoid wasting space */
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break;
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}
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default: {
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if (seminfo) save_and_next(ls);
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else next(ls);
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}
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}
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} endloop:
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if (seminfo)
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seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + sep,
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luaZ_bufflen(ls->buff) - 2 * sep);
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}
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static void esccheck (LexState *ls, int c, const char *msg) {
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if (!c) {
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if (ls->current != EOZ)
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save_and_next(ls); /* add current to buffer for error message */
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lexerror(ls, msg, TK_STRING);
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}
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}
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static int gethexa (LexState *ls) {
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save_and_next(ls);
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esccheck (ls, lisxdigit(ls->current), "hexadecimal digit expected");
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return luaO_hexavalue(ls->current);
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}
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static int readhexaesc (LexState *ls) {
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int r = gethexa(ls);
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r = (r << 4) + gethexa(ls);
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luaZ_buffremove(ls->buff, 2); /* remove saved chars from buffer */
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return r;
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}
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static unsigned long readutf8esc (LexState *ls) {
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unsigned long r;
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int i = 4; /* chars to be removed: '\', 'u', '{', and first digit */
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save_and_next(ls); /* skip 'u' */
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esccheck(ls, ls->current == '{', "missing '{'");
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r = gethexa(ls); /* must have at least one digit */
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while (cast_void(save_and_next(ls)), lisxdigit(ls->current)) {
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i++;
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esccheck(ls, r <= (0x7FFFFFFFu >> 4), "UTF-8 value too large");
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r = (r << 4) + luaO_hexavalue(ls->current);
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}
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esccheck(ls, ls->current == '}', "missing '}'");
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next(ls); /* skip '}' */
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luaZ_buffremove(ls->buff, i); /* remove saved chars from buffer */
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return r;
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}
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static void utf8esc (LexState *ls) {
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char buff[UTF8BUFFSZ];
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int n = luaO_utf8esc(buff, readutf8esc(ls));
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for (; n > 0; n--) /* add 'buff' to string */
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save(ls, buff[UTF8BUFFSZ - n]);
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}
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static int readdecesc (LexState *ls) {
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int i;
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int r = 0; /* result accumulator */
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for (i = 0; i < 3 && lisdigit(ls->current); i++) { /* read up to 3 digits */
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r = 10*r + ls->current - '0';
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save_and_next(ls);
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}
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esccheck(ls, r <= UCHAR_MAX, "decimal escape too large");
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luaZ_buffremove(ls->buff, i); /* remove read digits from buffer */
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return r;
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}
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static void read_string (LexState *ls, int del, SemInfo *seminfo) {
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save_and_next(ls); /* keep delimiter (for error messages) */
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while (ls->current != del) {
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switch (ls->current) {
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case EOZ:
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lexerror(ls, "unfinished string", TK_EOS);
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break; /* to avoid warnings */
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case '\n':
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case '\r':
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lexerror(ls, "unfinished string", TK_STRING);
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break; /* to avoid warnings */
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case '\\': { /* escape sequences */
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int c; /* final character to be saved */
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save_and_next(ls); /* keep '\\' for error messages */
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switch (ls->current) {
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case 'a': c = '\a'; goto read_save;
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case 'b': c = '\b'; goto read_save;
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case 'f': c = '\f'; goto read_save;
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case 'n': c = '\n'; goto read_save;
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case 'r': c = '\r'; goto read_save;
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case 't': c = '\t'; goto read_save;
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case 'v': c = '\v'; goto read_save;
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case 'x': c = readhexaesc(ls); goto read_save;
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case 'u': utf8esc(ls); goto no_save;
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case '\n': case '\r':
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inclinenumber(ls); c = '\n'; goto only_save;
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case '\\': case '\"': case '\'':
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c = ls->current; goto read_save;
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case EOZ: goto no_save; /* will raise an error next loop */
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case 'z': { /* zap following span of spaces */
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luaZ_buffremove(ls->buff, 1); /* remove '\\' */
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next(ls); /* skip the 'z' */
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while (lisspace(ls->current)) {
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if (currIsNewline(ls)) inclinenumber(ls);
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else next(ls);
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}
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goto no_save;
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}
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default: {
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esccheck(ls, lisdigit(ls->current), "invalid escape sequence");
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c = readdecesc(ls); /* digital escape '\ddd' */
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goto only_save;
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}
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}
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read_save:
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next(ls);
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/* go through */
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only_save:
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luaZ_buffremove(ls->buff, 1); /* remove '\\' */
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save(ls, c);
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/* go through */
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no_save: break;
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}
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default:
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save_and_next(ls);
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}
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}
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save_and_next(ls); /* skip delimiter */
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seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + 1,
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luaZ_bufflen(ls->buff) - 2);
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}
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// ls分词器状态管理; seminfo语义信息
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static int llex (LexState *ls, SemInfo *seminfo) {
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// buff中缓存清零
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luaZ_resetbuffer(ls->buff);
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for (;;) {
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switch (ls->current) {
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case '\n': case '\r': { /* line breaks */
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// 跳过换行符
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inclinenumber(ls);
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break;
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}
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case ' ': case '\f': case '\t': case '\v': { /* spaces */
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// 跳过空白字符
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next(ls);
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break;
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}
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case '-': { /* '-' or '--' (comment) */
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next(ls);
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// 返回 - 号
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if (ls->current != '-') return '-';
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/* else is a comment */
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next(ls);
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if (ls->current == '[') { /* long comment? */
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// 跳过长注释
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size_t sep = skip_sep(ls);
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luaZ_resetbuffer(ls->buff); /* 'skip_sep' may dirty the buffer */
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if (sep >= 2) {
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read_long_string(ls, NULL, sep); /* skip long comment */
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luaZ_resetbuffer(ls->buff); /* previous call may dirty the buff. */
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break;
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}
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}
|
||
// 跳过短注释
|
||
/* else short comment */
|
||
while (!currIsNewline(ls) && ls->current != EOZ)
|
||
next(ls); /* skip until end of line (or end of file) */
|
||
break;
|
||
}
|
||
case '[': { /* long string or simply '[' */
|
||
size_t sep = skip_sep(ls);
|
||
if (sep >= 2) {
|
||
read_long_string(ls, seminfo, sep);
|
||
return TK_STRING;
|
||
}
|
||
else if (sep == 0) /* '[=...' missing second bracket? */
|
||
lexerror(ls, "invalid long string delimiter", TK_STRING);
|
||
return '[';
|
||
}
|
||
case '=': {
|
||
next(ls);
|
||
if (check_next1(ls, '=')) return TK_EQ; /* '==' */
|
||
else return '=';
|
||
}
|
||
case '<': {
|
||
next(ls);
|
||
if (check_next1(ls, '=')) return TK_LE; /* '<=' */
|
||
else if (check_next1(ls, '<')) return TK_SHL; /* '<<' */
|
||
else return '<';
|
||
}
|
||
case '>': {
|
||
next(ls);
|
||
if (check_next1(ls, '=')) return TK_GE; /* '>=' */
|
||
else if (check_next1(ls, '>')) return TK_SHR; /* '>>' */
|
||
else return '>';
|
||
}
|
||
case '/': {
|
||
next(ls);
|
||
if (check_next1(ls, '/')) return TK_IDIV; /* '//' */
|
||
else return '/';
|
||
}
|
||
case '~': {
|
||
next(ls);
|
||
if (check_next1(ls, '=')) return TK_NE; /* '~=' */
|
||
else return '~';
|
||
}
|
||
case ':': {
|
||
next(ls);
|
||
if (check_next1(ls, ':')) return TK_DBCOLON; /* '::' */
|
||
else return ':';
|
||
}
|
||
case '"': case '\'': { /* short literal strings */
|
||
read_string(ls, ls->current, seminfo);
|
||
return TK_STRING;
|
||
}
|
||
case '.': { /* '.', '..', '...', or number */
|
||
save_and_next(ls);
|
||
if (check_next1(ls, '.')) {
|
||
if (check_next1(ls, '.'))
|
||
return TK_DOTS; /* '...' */
|
||
else return TK_CONCAT; /* '..' */
|
||
}
|
||
else if (!lisdigit(ls->current)) return '.';
|
||
else return read_numeral(ls, seminfo);
|
||
}
|
||
case '0': case '1': case '2': case '3': case '4':
|
||
case '5': case '6': case '7': case '8': case '9': {
|
||
return read_numeral(ls, seminfo);
|
||
}
|
||
case EOZ: {
|
||
return TK_EOS;
|
||
}
|
||
default: {
|
||
if (lislalpha(ls->current)) { /* identifier or reserved word? */
|
||
TString *ts;
|
||
do {
|
||
save_and_next(ls);
|
||
} while (lislalnum(ls->current));
|
||
ts = luaX_newstring(ls, luaZ_buffer(ls->buff),
|
||
luaZ_bufflen(ls->buff));
|
||
seminfo->ts = ts;
|
||
if (isreserved(ts)) /* reserved word? */
|
||
return ts->extra - 1 + FIRST_RESERVED;
|
||
else {
|
||
return TK_NAME;
|
||
}
|
||
}
|
||
else { /* single-char tokens ('+', '*', '%', '{', '}', ...) */
|
||
int c = ls->current;
|
||
next(ls);
|
||
return c;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
|
||
void luaX_next (LexState *ls) {
|
||
ls->lastline = ls->linenumber;
|
||
if (ls->lookahead.token != TK_EOS) { /* is there a look-ahead token? */
|
||
ls->t = ls->lookahead; /* use this one */
|
||
ls->lookahead.token = TK_EOS; /* and discharge it */
|
||
}
|
||
else
|
||
ls->t.token = llex(ls, &ls->t.seminfo); /* read next token */
|
||
}
|
||
|
||
|
||
int luaX_lookahead (LexState *ls) {
|
||
lua_assert(ls->lookahead.token == TK_EOS);
|
||
ls->lookahead.token = llex(ls, &ls->lookahead.seminfo);
|
||
return ls->lookahead.token;
|
||
}
|
||
|